Multi-stress aging of stator bars with electrical, thermal, and mechanical stresses as simultaneous acceleration factors

Accelerated aging tests have been carried on stator bars under simultaneous electrical, thermal and mechanical multi-stress conditions, using a simulated three-phase model stator. Over each thermal load cycle, the partial discharge activity has been found to be a strong function of temperature. Tests at twice rated electrical stress did not result in any bar specimen failures up to a total of 1500 load cycles. However, when the three phase load current was increased above its rated value, current-limited type failures were observed to occur below 1000 load cycles, thereby indicating a marked influence of thermal and mechanical stresses associated with the elevated three phase load current.

[1]  L. Simoni,et al.  A General Approach to the Endurance of Electrical Insulation under Temperature and Voltage , 1981, IEEE Transactions on Electrical Insulation.

[2]  G. Stone,et al.  A Quality Control Test for High Voltage Stator Insulation , 1987, IEEE Electrical Insulation Magazine.

[3]  R. Bartnikas,et al.  Accelerated Life Testing of Wet Cable Specimens at Frequencies Above 60 Hz , 1980, IEEE Transactions on Power Apparatus and Systems.

[4]  J. C. Bromley,et al.  Relationship between partial discharge pulse height analysis and subsequent voltage endurance of stator bars and coils , 1992 .

[5]  R. Morin,et al.  A three-phase multi-stress accelerated electrical aging test facility for stator bars , 2000 .

[6]  George J. Anders,et al.  Motor and generator insulation life estimation , 1992 .

[7]  W. McDermid.  A utility's evaluation of a stator bar insulation system operating at increased electric stress , 1997, Proceedings: Electrical Insulation Conference and Electrical Manufacturing and Coil Winding Conference.

[8]  R. Bartnikas,et al.  Multiple stress aging of solid-dielectric extruded dry-cured insulation systems for power transmission cables , 1994 .

[9]  E. Brancato,et al.  Insulation Aging a Historical and Critical Review , 1978, IEEE Transactions on Electrical Insulation.

[10]  K. Srivastava,et al.  Power and Communication Cables , 2003 .

[11]  Robert J. Ross,et al.  Analysis of in-service aged stator bars , 1995 .

[12]  Greg C. Stone,et al.  A thermal cycling type test for generator stator winding insulation , 1991 .

[13]  R. E. Drapper,et al.  Development of a vertical generator stator bar insulation system for operation at increased stress , 1997, Proceedings: Electrical Insulation Conference and Electrical Manufacturing and Coil Winding Conference.

[14]  Ian Culbert,et al.  Assessment of insulation condition in rotating machine stators , 1992 .

[15]  H. Yoshida,et al.  Insulation Diagnosis for Rotating Machine Insulation , 1986, IEEE Transactions on Electrical Insulation.

[16]  Thomas W. Dakin,et al.  Electrical Insulation Deterioration Treated as a Chemical Rate Phenomenon , 1948, Transactions of the American Institute of Electrical Engineers.

[17]  A. W. W. Cameron,et al.  A Utility's Functional Evaluation Tests for High-Voltage Stator Insulation , 1959, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[18]  Michael J. Kurtz,et al.  Experience with PDA diagnostic testing on hydraulic generators , 1988 .

[19]  T. Tsukui,et al.  Correlations between Nondestructive and Destructive Tests on High-Voltage Coil Insulations for Rotating Miachines , 1981, IEEE Transactions on Electrical Insulation.

[20]  R. Bartnikas,et al.  Engineering Dielectrics Volume I Corona Measurement and Interpretation , 1979 .

[21]  H. G. Sedding,et al.  The ability of diagnostic tests to estimate the remaining life of stator insulation , 1988 .

[22]  R. Bartnikas,et al.  Spark-to-glow discharge transition due to increased surface conductivity on epoxy resin specimens , 1993 .